Accession Number : AD1030075

Title :   Microwave Photonic Architecture for Direction Finding of LPI Emitters: Front End Analog Circuit Design and Component Characterization

Descriptive Note : Technical Report


Personal Author(s) : Tan,Chew K

Full Text :

Report Date : 01 Sep 2016

Pagination or Media Count : 125

Abstract : Direction finding (DF) systems are critical components in electronic warfare intercept receivers. Many existing radio frequency DF techniques use a non-linear frequency down-conversion process that generates spurious frequencies that can hide the signals-of-interest. In addition, these systems suffer from a limited bandwidth and poor resolution (e.g., 2 degrees). To overcome these limitations, a miniature microwave photonic phase-sampling DF technique is investigated in this thesis. This front-end design uses a combination of integrated optical Mach-Zehnder phase detectors to measure the emitters phase difference with the largest baseline being 23 cm. The front-end components were characterized to ensure accuracy in the resolved angle-of-arrival (AOA). The front-end design was constructed to be modular in order to facilitate testing and verification of analog components accuracy. Signal processing with a class IV laser required particular attention to ensure that any stray radiation or leakage was isolated. Testing with low probability of intercept (LPI) waveform modulation consisted of using a linear frequency-modulated continuous wave (FMCW) and a phase coded P4 modulation, both at 2.4 GHz, in an anechoic chamber. Measurements were taken to quantify the DF receiver sensitivity was R = -62.96 dBm. It was demonstrated that the system was capable of estimating the AOA for the FMCW signal with a root-mean square (RMS) error of 0.29 degree at 1 degree resolution and a P4 modulation RMS error of 0.32 degree at 1 degree resolution.

Descriptors :   direction finding , INTERFEROMETRY , angle of arrival , EMITTERS , INTEGRATED OPTICS , microwave photonics , signal generators , optical modulators , low noise amplifiers

Distribution Statement : APPROVED FOR PUBLIC RELEASE